Uncertain; but perhaps an agent noun related to Ancient Greek μαγγανεύω (manganeúō, “enchant, use charms”) and secondarily “trick out, dress artificially”, from the noun μάγγανον (mánganon, “philtre, charm, means for bewitching others”). Buck suggests that Latin mangō is a loanword based (ultimately or otherwise) on the Greek noun. Alternatively, derived from manus (“hand”) via an unattested verb such as *manicō or *manigō (“handle, manage; trade, deal?”) (both requiring an unusual syncope of the verb suffix, the former also requiring an unusual voicing of /k/) + -ō (agent noun suffix). This would make it related to manceps (“purchaser; contractor”) and mancipium (“property, slave”), whence perhaps the sense of “slave-trader”. The semantic trajectory would be similar to that of German handeln (“to handle; to trade, deal”), ultimately from Proto-Germanic *handuz (“hand”).